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6.4 Bi-directional data ports
The input circuitry of the bi-directional data ports is identical to the input circuitry for the sensor data input ports
described in the preceding section. The output circuitry consists of a differential line driver IC (Texas
Instruments AM26LV31E) and is shown in Figure 54.
From UART
Figure 54 Data output port schematic
Each bi-directional data port input is isolated from other data port inputs and from the
transceivers internal power supply. The bi-directional data port outputs are not isolated from each
other or the transceivers internal power supply. The transceivers internal power supply is fully
isolated from the external supply.
6.5 Output drive capability of bi-directional ports
Bi-directional ports can supply an output current of up to 30mA. The output voltages are 0 (low) and 3.3V (high).
Effective load resistance should be in excess of 100 Ohms.
6.6 DGPS port
The DPGS correction port is intended for connection to a DGPS beacon receiver. The port has the same
physical characteristics as the bi-directional data ports as described in the preceding sections. If connection of
a beacon receiver is not required this port can be re-configured as an additional bi-directional port to
IEC61162-2. See section 3.16 for port configuration options.
6.7 RS232 port
The RS232 port carries IEC61162 data via RS232 and is intended for connection to a PC during installation
and service. The port can also be used to connect to PC based charting applications for display of AIS data.
6.8 Input data sentence formats
All data input is via IEC61162 / NMEA 0183 sentences. The sentences used by the AIS transceiver are
documented in the subsequent sections. The sentence structure tables describe each field in the sentence
starting from the left most field (field 1) after the sentence identifier. All sentences are terminated with the
IEC61162 checksum shown as '*hh'. For details of the checksum calculation please refer to IEC61162-1.
GND
220 Ohms
@100MHz
10 Ohms
B
Data output port
A
220 Ohms
10 Ohms
@100MHz
GND
100 Ohms
Technical reference
Page 57
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